The present invention relates to methods and apparatuses for electrically stimulating muscles and, more particularly, to a computer controlled system and method for exercising paralyzed muscles through programmed electrical stimulation.
Each year thousands of persons are permanently paralyzed as a result of traumas sustained by their spinal cords. Often, the trauma is such that there is no direct damage to most of the muscles in the victim's body, but communication between brain and the lower spinal cord is eliminated, which results in a permanent loss of control of certain muscle groups. This loss of control causes a number of additional problems in the body of the victim. The first of these is the atrophy of the uncontrolled muscle from disuse. Disuse atrophy is distinguishable from other types of atrophy in that the muscle and associated tendons are still functionally healthy, but because of lack of use, the muscle wastes away and loses much of its protein content.
A second problem is demineralization of the bones associated with the uncontrolled muscles due to the lack of muscle activity. After bone demineralization has become advanced, the simple act of passively moving the leg of a victim can break a bone or crack a joint. In addition, deterioration of the tendons and other soft tissue occurs, as well as a severe wasting away of cardiac tissue. The latter results in a compromised cardiovascular system which predisposes the victim's body to secondary cardiovascular disease and secondary renal disease. All of these conditions are commonly found in the pathology of victims of spinal cord injury after chronic paralysis.
Until recently it was believed that a spinal cord injury could not be cured. Consequently very little was done for persons having spinal cord injury aside from trying to maintain their bodily health. However, recent advances in spinal cord research have given new hope to those who are paralyzed due to spinal injury. Furthermore, techniques have now been developed for causing movement of a victim's hands or legs, through functional electrical stimulation. This latter development makes it possible to exercise paralyzed limbs and keep them in good physical condition. Hopefully such conditioning will enable restoration of useful functional activity when a cure for spinal cord injury has been developed. Such conditioning also helps to reverse or eliminate the secondary diseases associated with spinal cord injury. Elimination or reversal of these diseases may greatly reduce medical costs and increase the longevity of the spinal injury victim.
Examples of systems for exercising paralyzed limbs through functional electrical stimulation may be found in Petrofsky et al U.S. Pat. Nos. 4,480,830 and 4,499,900, the disclosures of which are incorporated herein by reference. Such systems can work the muscles to precise levels and increase the metabolic loads as appropriate to produce muscle build-up. With these exercise systems it is possible to bring the muscle back to normal strength and to retrain the cardiovascular system. However, the health of the patient requires that the program be carried out progressively under the direction of an attending physician. During the course of the program it is important that limits be set on the work load and on physiological parameters such as body temperatures, heart rate and blood pressure. The exercise system must include means for measuring such variables, and provision must be made for terminating an exercise routine whenever one of the prescribed limits has been exceeded. If the physician is not present during the exercise, then provision must be made for generating a report of the performance of the patient during the routine, so that the prescribed limits may be appropriately adjusted.